Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.1 (protein kinase)
 81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of some protein kinase effectors on phosphohydrolase and transport activities of yeast vacuoles have been studied. The platelet-activating factor (PAF), a plant vacuolar protein kinase C stimulator, had a protonophoric and membrane-damaging effects on yeast vacuoles and inhibited the ATP-dependent delta mu H+ formation and ATP-dependent secondary transport but stimulated the ATPase and pyrophosphatase hydrolase activities by abrogating proton control. PAF increasing the tonoplast permeability for the corresponding substrates also stimulated pyrophosphatase, polyphosphatase and alkaline phosphatase activities. Lysolipid sphingosine, a plant vacuolar protein kinase C inhibitor, poorly stimulated the ATPase activity and the ATP-dependent formation of Em in isolated yeast vacuoles, while the pyrophosphatase activity increased by 200%. Other hydrolase activities tested were insensitive to the effect of the lysolipid. Sphingosine inhibited the ATP-dependent citrate transport only insignificantly. Heparin, an effective casein kinase inhibitor, suppressed the ATPase and polyphosphatase activities in isolated yeast vacuoles. The polyphosphatase activity was inhibited both in the vacuolar sap and the tonoplast solubilized by a Zwittergent TM-314, in contrast with the ATPase activity which was inhibited by heparin only in isolated vacuoles. Heparin is suggested to inhibit polyphosphatase by directly influencing the enzyme.
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PMID:[The effect of PAF, sphingosine and heparin on certain phosphohydrolase and transport activity of yeast vacuoles]. 794 17

Inorganic polyphosphate (poly P), chains of hundreds of phosphate residues linked by "high-energy" bonds as in ATP, has been conserved from prebiotic times in all cells. Poly P is essential for a wide variety of functions in bacteria, including virulence in pathogens. In this study, we observe the unique and many-fold stimulation by poly P in vitro of the protein kinase mTOR (mammalian target of rapamycin). To explore the role of poly P in mammalian cells, a yeast polyphosphatase, PPX1, was inserted into the chromosomes of MCF-7 mammary cancer cells. The transfected cells are markedly deficient in their response to mitogens, such as insulin and amino acids, as seen in their failure to activate mTOR to phosphorylate one of its substrates, PHAS-I (the initiation factor 4E-binding protein). In addition, the transfected cells are severely reduced in their growth in a serum-free medium. On the basis of these findings, we suggest that poly P (and/or PPX1) serves as a regulatory factor in the activation of mTOR in the proliferative signaling pathways of animal cells.
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PMID:Inorganic polyphosphate stimulates mammalian TOR, a kinase involved in the proliferation of mammary cancer cells. 1297 Apr 65